U.S. patent application number 12/713424 was filed with the patent office on 2011-09-01 for light guide for improving device lighting.
This patent application is currently assigned to RESEARCH IN MOTION LIMITED. Invention is credited to Antanas Matthew BROGA, Hsin Chin LEE.
Application Number | 20110210921 12/713424 |
Document ID | / |
Family ID | 44505012 |
Filed Date | 2011-09-01 |
United States Patent
Application |
20110210921 |
Kind Code |
A1 |
LEE; Hsin Chin ; et
al. |
September 1, 2011 |
LIGHT GUIDE FOR IMPROVING DEVICE LIGHTING
Abstract
A light guide guides light from a light emitter that is adjacent
to an aperture of an electronic device. The light is eventually
emitted from the aperture, to thereby provide lighting. The light
guide can include a plurality of prisms which can thereby permit
reduction in the overall thickness of the electronic device.
Inventors: |
LEE; Hsin Chin; (Waterloo,
CA) ; BROGA; Antanas Matthew; (Cambridge,
CA) |
Assignee: |
RESEARCH IN MOTION LIMITED
Waterloo
CA
|
Family ID: |
44505012 |
Appl. No.: |
12/713424 |
Filed: |
February 26, 2010 |
Current U.S.
Class: |
345/170 |
Current CPC
Class: |
G02B 6/0036 20130101;
G06F 3/0202 20130101 |
Class at
Publication: |
345/170 |
International
Class: |
G06F 3/02 20060101
G06F003/02 |
Claims
1. A light guide configured for positioning proximate to a light
emitter in an electronic device; said light guide comprising: a
first prism having a first position in relation to said light
emitter; said first prism having a first boundary defined by a
first length and a first angle in relation to a plane normal to a
surface of said light emitter; and, a second prism having a second
position in relation to said light emitter; said second prism
having a second boundary defined by a second length and a second
angle in relation to said plane; wherein said first position is
closer to said light emitter than said second position and said
second angle is less than said first angle.
2. The light guide of claim 1 wherein said first angle is between
about one degree and about eighty degrees.
3. The light guide of claim 1 wherein said first angle is about
forty degrees.
4. The light guide of claim 1 wherein said first angle is between
about thirty degrees and about fifty degrees.
5. The light guide of claim 1 wherein said second angle is between
about one degree and about eighty degrees.
6. The light guide of claim 1 wherein said second angle is about
twenty degrees.
7. The light guide of claim 1 wherein said second angle is between
about ten degrees and about thirty degrees.
8. The light guide of claim 1 wherein said second angle is
different than said first angle.
9. The light guide of claim 1 further comprising: a third prism
having a third position in relation to said light emitter; said
third prism having a third boundary defined by a third length and a
third angle in relation to said plane; wherein said second position
is closer to said light emitter than said third position and said
third angle is less than said second angle.
10. The light guide of claim 1 comprising a plurality of additional
prisms; each of said prisms being substantially square in shape
arranged in a grid; each of said additional prisms having surfaces
defined by additional lengths and additional angles in relation to
said plane, each decreasing in size according to a distance from
said light emitter.
11. The light guide of claim 1 wherein at least one of said prisms
is a pyramid shape.
12. The light guide of claim 11 wherein said pyramid shape is one
of a tetrahedron, a square pyramid, and a pentagonal pyramid.
13. The light guide of claim 11 wherein said pyramid shape has two
pairs of sides; each said side in each said pair being of the same
length; each of said pairs having different lengths.
14. The light guide of claim 1 wherein said first prism is conical
and said second prism is a concentric annular prism surrounding
said first prism.
15. The light guide of claim 1 wherein said first position centers
said first prism in relation to said light emitter.
16. The light guide of claim 1 wherein said first position places
said first prism off center in relation to said light emitter.
17. An electronic device comprising: a light emitter; a first prism
having a first position in relation to said light emitter; said
first prism having a first surface boundary defined by a first
length and a first angle in relation to emitted light from a plane
normal to a surface of said light emitter; said first prism
configured to reflect at least a portion of said emitted light away
from said first surface; and, a second prism having a second
position in relation to said light emitter; said second prism
having a second boundary defined by a second length and a second
angle in relation to said plane; wherein said first position is
closer to said light emitter than said second position and said
second angle is less than said first angle. an aperture proximate
to said light emitter for transmitting light that is reflected from
said first prism and said second prism.
18. The electronic device of claim 17 wherein said aperture is
disposed on a key of a keyboard.
19. The electronic device of claim 17 wherein said aperture is
configured for illuminating a surface of said electronic device and
said device one of a cellular telephone, a handheld remote control
unit, a garage door opener, a portable email paging device, a
camera, a portable music player, a portable video player, a
portable video game player, a handheld global positioning system
(GPS) device, a keyboard for a desktop computers, a video game
control pad.
20. The electronic device of claim 17 wherein said aperture is
configured for a backlight of a display on said electronic device.
Description
FIELD
[0001] The present specification relates generally to lighting
technologies and more particularly relates to a light guide for
providing lighting to an electronic device.
BACKGROUND
[0002] Portable electronic devices, cellular telephones and other
devices frequently include a display as well as one or more input
devices. Low light conditions, however, can dramatically impact
device usability, particularly where the emitted light from the
display can make it difficult or impossible to see an input device
near that display. To compensate for low light conditions, small
lights may be included so as to light the input device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The following Figures show certain exemplary
embodiments:
[0004] FIG. 1 is a front view of a non-limiting example of a
portable electronic device to which light guides according to the
present specification can be applied.
[0005] FIG. 2 is an exploded view of the portable electronic device
of FIG. 1.
[0006] FIG. 3 is an end view of the device of FIG. 1.
[0007] FIG. 4 shows one of the keys from FIG. 3 in greater
detail.
[0008] FIG. 5 is front view of the substrate from FIG. 2.
[0009] FIG. 6 is a sectional view of the substrate of FIG. 5
providing an example of a light-guide.
[0010] FIG. 7 shows a detail of a portion of the light-guide shown
in FIG. 6.
[0011] FIG. 8 shows the light-guide of FIG. 6 with the light
emitter emitting light.
[0012] FIG. 9 shows a top view of a light assembly in accordance
with another non-limiting example.
[0013] FIG. 10 shows another top view of a light assembly in
accordance with another non-limiting example.
[0014] FIG. 11 shows an example of a three-dimensional perspective
view of a light-guide.
[0015] FIG. 12 shows an example of a variation of a sectional view
of a light-guide providing a pitch between adjacent prisms.
DETAILED DESCRIPTION
[0016] This specification pertains to light guides that direct
light generated by a light emitter for emission from an electronic
device. For example, in an electronic device having an input device
such as a keyboard or keypad, the light guide directs light from
the emitter towards an aperture associated with an input device. As
will be discussed further below, the aperture can be any structure
that defines an opening, or a window, or transparent material, or
translucent material, or any other structure by which the light may
issue from the electronic device. In one illustrative embodiment,
an aperture may be an illuminated key of a keyboard. The
illumination of the key comes from light generated by the light
emitter and directed to the key by the light guide.
[0017] FIG. 1 shows a schematic representation of a non-limiting
example of a portable electronic device 50 to which light guides,
as discussed in greater detail below, can be applied. It is to be
understood that portable electronic device 50 is purely exemplary,
and it will be apparent to those skilled in the art that a variety
of different portable electronic device structures are
contemplated. Indeed variations on portable electronic device 50
can include, without limitation, a cellular telephone, a handheld
remote control unit, a garage door opener, a portable email paging
device, a camera, a portable music player, a portable video player,
a portable video game player and a handheld global positioning
system (GPS) device. Other contemplated variations include devices
which are not necessarily portable, such as keyboards for desktop
computers, video game control pads and traditional telephone
handsets.
[0018] Device 50 comprises a chassis 54 that supports a display 58.
Display 58 can comprise one or more light emitters such as an array
of light emitting diodes (LED), liquid crystals, plasma cells, or
organic light emitting diodes (OLED). Other types of light emitters
are contemplated. In general, display 58 can be any kind of
apparatus for displaying visual information. Display 58 is
typically controlled by one or more processing units (not shown)
supported within chassis 54. It should be understood that other
types of electronic devices which do not include displays and which
can utilize the light guides discussed herein are contemplated, and
accordingly, display 58 is optional for implementing light guides
as discussed herein.
[0019] Device 50 also comprises a keyboard 62. Keyboard 62
comprises a plurality of keys 66. For ease of explanation, only the
key bearing the letter "J" is indicated with reference 66 in FIG.
2. Also for ease of explanation, device 50 is shown as only having
twelve keys, labeled "A" through "I". However, it is to be
understood that this specification is not limited to any particular
structure, spacing, pitch or shape of keyboard 62, and the
depiction in FIG. 1 is purely exemplary. For example, full or
reduced "QWERTY" keyboards are contemplated. As another example,
numeric keyboards as commonly employed on telephones or handheld
remote control units are also contemplated. Other types of
keyboards are contemplated. It is also to be understood that while
the present embodiment is directed to lighting of a keyboard, such
as keyboard 66, the present specification also contemplates the
lighting of other components, such as touch-pads, joysticks,
trackballs, track-wheels, keypads, instrument panels in aircraft or
other vehicles, a backlight for a display, and any other component
of electronic devices that includes lighting so that the electronic
device can be seen in low-light environments. It is also to be
understood that light guides can be applied to other, more general
lighting applications associated with apertures on electronic
devices, such as illuminated labels, symbols or indicator lights
not associated with a particular input device.
[0020] FIG. 2 shows an exploded view of device 50. Again, it is to
be understood that the components shown in FIG. 2 are purely
exemplary and that other configurations of the internal components
of a particular device which utilizes a light guide as discussed
herein are contemplated. FIG. 2 shows chassis 54 comprising a base
68 and a cover 70. Cover 70 is typically made from a plastic
material and comprises a window 72 and a plurality of openings 74,
with one opening 74 for each key 66. Cover 70 may or may not be
partially translucent or transparent; but in general, window 72 may
be an opening, or comprise a substantially transparent material so
that information on display 58 can be presented and seen. As noted
previously, light emitted from display 58 can make it difficult to
discern light issuing from keyboard 62 near display 58.
[0021] As best seen in FIG. 2, display 58 is mounted to base 68,
although the electrical and mechanical connections between display
58 and base 68 are not shown for ease of explanation. Base 68 also
comprises a plurality of light emitters 90 which can be implemented
using, for example, light emitting diodes (LED). FIG. 2 also shows
a substrate 78 which is mounted to base 68, below display 58,
although the mechanical connections between substrate 78 and base
68 are also omitted for ease of explanation. Substrate 78 will be
discussed in greater detail below.
[0022] In a present exemplary embodiment, keyboard 62 is
implemented as a continuous flexible polymeric membrane 74 with a
plurality of projections therealong, each projection representing a
separate key 66. The use of a continuous flexible polymeric
membrane 74 may entail one or more advantages, such as advantages
of cost or less susceptibility to contamination, but the concepts
described herein are not limited to keyboards or other input
devices that include such membranes.
[0023] When device 50 is assembled, display 58 is mounted to base
68, and substrate 78 is mounted to base 68 near display 58.
Keyboard 62 is then placed over substrate 78, and finally cover 70
is disposed over display 58 and keyboard 62. Mechanical
connections, such as snaps, screws, glue or other types of
fasteners can be used to affix these components and attach cover 70
to base 68.
[0024] Referring now to FIG. 3, an end view of device 50 is shown.
As can be seen in FIG. 3, device 50 can be characterized by a
thickness "T". As will be discussed further below, the light guides
discussed herein can permit device 50 to be structured to have a
thickness "T", that is reduced at least in relation to devices 50
that otherwise do not incorporate the light guides discussed
herein.
[0025] As best seen in FIG. 4, membrane 74 is also opaque (i.e.
partially transmissive or completely non-transmissive of light),
except that an aperture 76 is provided for each letter (or other
symbol) representing each key. In FIG. 4, aperture 76 is in the
shape of the letter "J" shown on key 66. It should be understood
that the exact type and shape and structure of contemplated
aperture 76 is not particularly limited, and can thus include
structures that are simple windows or cut-out openings (i.e. no
material is provided), or apertures that can be formed from a
material that is transparent, or is at least partially transmissive
of light. In a present non-limiting embodiment, aperture 76 for
each letter is more transmissive of light than the remainder of the
structure of membrane 74. This feature is illustrated in FIG. 4,
where light L from a light source (associated with a light guide,
discussed further below) is shown as incident on the side of
keyboard 62 that is closest to substrate 78, however, due to the
opaque nature of membrane 74, only transmitted light TL actually
travels through the J-shaped aperture 76 on the "J" key 66. In this
manner, when light L is present, the individual letters or symbols
on keyboard 62 are visible in zero or low-light conditions as
transmitted light TL creates an appearance of illumination of each
of the letters or symbols on each key 66. Again, note that keyboard
62, and in particular key 66 shown in FIG. 4, represents just one
type of aperture contemplated. Indeed, the principles of light
direction described below can be applied to the other types of
apertures, whether or not associated with input devices, which are
distinct from membrane 74. The underside of membrane 74 can also be
provided with a white reflective layer, such that light L that does
not become transmitted light TL becomes reflected light R.
Reflected light R can undergo further internal reflections and
eventually be emitted from another aperture from another key on
keyboard 62.
[0026] Referring now to FIG. 5, substrate 78 is shown in greater
detail. FIG. 5 thus shows a plurality of locations 82 to
accommodate mechanical communication between keys 66 and
corresponding keyboard switches (not shown) which are typically
provided on base 68. For simplicity, only one location 82 is
labelled in FIG. 5, which corresponds to the key 66 shown in FIG.
4. Depressing of a key 66 results in activation of a switch within
location 82 in the usual manner.
[0027] Substrate 78 comprises a plurality of light assemblies 86.
Each light assembly 86 is mounted in a distributed manner across
substrate 78. In the specific example of FIG. 5, six light
assemblies 86 are provided, but it should be understood that the
number of light assemblies is not particularly limited and can be
selected according to the overall size and shape of a particular
keyboard 62 or other input devices or other types of apertures
which are to be illuminated. However, as will be discussed further
below, the spacing between each light assembly 86, and the
structure of each light assembly 86, is configured such that the
amount of light emitted from each key 66 (i.e. transmitted light TL
in FIG. 4), when device 50 is assembled, is substantially uniform.
Expressed in other words, the amount of transmitted light TL from
each aperture 76 of each key 66 will be substantially the same.
[0028] FIG. 6 shows a single light assembly 86 in accordance with
one example of this specification. FIG. 6 shows a first surface 102
and a second surface 104 of substrate 78. Because FIG. 6 provides a
sectional view, surfaces 102 and 104 appear as edges. As indicated
by FIG. 6 and as described below, first surface 102 and a second
surface 104 may be substantially planar but may also include
physical features such that they are not strictly planar. Light
assembly 86 is formed within substrate 78 and between first surface
102 and second surface 104. First surface 102 and second surface
104 thus define the thickness of substrate 78. Advantageously,
substrate 78, according to exemplary embodiments herein, can have a
thickness of about 1.2 millimeters thereby providing structure for
reducing an overall thickness of device 50 while still providing
substantially uniform lighting across keyboard 62. For convenience
and subsequent reference, FIG. 6 also shows a dashed center-line 91
that passes through the center of light assembly 86 and through the
center of light emitter 90. In a present embodiment, center-line 91
also happens to be normal to first surface 102 and second surface
104, but it is to be understood that in variants where first
surface 102 or second surface 104 or both of them are non-planar, a
conceptual center-line still exists. Similarly, FIG. 6 also shows a
dashed line that represents a plane 93 normal to center-line
91.
[0029] Explaining light assembly 86 further, light assembly 86 is
proximate to light emitter 90, and may be in physical contact with
light emitter 90. As viewed in FIG. 6, a pocket 92 may be formed
along first surface 102. Pocket 92 may be complementary in shape to
light emitter 90, and may fit over a respective light emitter 90 to
cover that light emitter 90 when substrate 78 is mounted to base
68. In can be noted in FIG. 6 that light emitter 90 is
substantially rectangular in cross sectional shape, but other
shapes are contemplated. Additionally, a light guide 94 is formed
along second surface 104. FIG. 6 also shows a gap 108 between
pocket 92 and light guide 94. In a present, non-limiting
embodiment, substrate 78 is a solid material and therefore gap 108
is also formed from that solid material. In a present embodiment
substrate 78 is either transparent, or substantially transparent,
polycarbonate or poly(methyl methacrylate) (PMMA). Accordingly, gap
108 will have an index of refraction, and those skilled in the art
will now recognize that light guide 94 can be configured so as to
consider any effects of that index of refraction associated with
gap 108. For example, polycarbonate has an index of refraction of
about 1.59 while PMMA has an index of refraction of about 1.49.
Likewise, light guides 94 can be implemented to account for
refraction resulting from air (or vacuum or material) within pocket
92 that exists between light emitter 90 and gap 108. In the present
embodiment, center-line 91 passes through the center of both light
guide 94 and light emitter 90, but, as will be explained in
relation to subsequent embodiments, the center of light guide 94
can be placed off-center from light emitter 90.
[0030] It should now be noted that substrate 78 and light
assemblies 86 can be formed using various manufacturing processes,
including injection molding. The various possible materials for
substrate 78 can also be chosen for ease of manufacture depending
on the selected manufacturing process.
[0031] It should now be understood that, while in the present
embodiment substrate 78 is a solid material, and light guide 94 and
pocket 92 are formed along edges of that solid material, an inverse
structure is also contemplated, whereby, for example, gap 108 is a
vacuum (or air or other gas), and light guide 94 itself formed from
a solid material.
[0032] Light guide 94 comprises a plurality of reflective prisms
98. In the specific example of FIG. 6, there are six prisms 98-1,
98-2, 98-3, 98-4, 98-5 and 98-6. Light guide 94 is a symmetric
structure, whereby prisms 98-1, 98-2 and 98-3 are a mirror-image of
prisms 98-4, 98-5 and 98-6. In general prisms 98 are elements that
refract light (and may also transmit or reflect light, depending on
the shape of the prism and the path of light through the prism).
Expressed differently, prisms 98 change the direction of rays of
emitted light EL from light emitter 90. Prisms 98 may have, but do
not necessarily have, one or more planar faces. Prisms 98 include
one or more boundaries, which represent the transition from one
medium to another. For example, prism 98 may have one or more
boundaries that transition from PMMA to air.
[0033] FIG. 7 shows prisms 98-1, 98-2 and 98-3 in greater detail,
and those skilled in the art will now recognize that the detail in
FIG. 7 likewise applies to prisms 98-4, 98-5 and 98-6. For the
present, non-limiting exemplary embodiment, prisms 98-1, 98-2 and
98-3 are defined according to certain dimensions as illustrated in
FIG. 7. As viewed in FIG. 7, each prism 98 is substantially
triangular in cross-sectional shape, and to help further illustrate
each prism 98, a cross-sectional triangle 100 is provided in dashed
lines and which is complementary to the substantially triangular
shape of each prism 98. More specifically, as viewed in FIG. 7,
prism 98-1 is substantially triangular in cross-sectional shape and
can be defined by a height H1, a length L1, a distance D1, and an
angle .theta.1. One side of the cross-sectional triangle 100-1 is
substantially parallel to the plane of the second surface 104 and
another side of the cross-sectional triangle 100-1 is substantially
perpendicular to the plane of the second surface 104, making
triangle 100-1 a right-angled triangle. As shown by FIG. 7, prism
98-1 is substantially triangular in cross-sectional shape in that
one or more corners of the substantially triangular cross-sections
may be rounded rather than sharp. Height H1 represents the
perpendicular distance between the plane of the second surface 104
and a first corner of triangle 100-1. Distance D1 represents the
perpendicular distance between the plane of the second edge 104 and
a second corner of triangle 100-1. Distance L1 represents the
length of the hypotenuse of triangle 100-1, the hypotenuse
generally being a boundary (or part of a boundary) of the prism
98-1. Angle .theta.1 represents the angle formed by the hypotenuse
of triangle 100-1 and the plane of the plane of the second surface
104. Angle .theta.1 also represents the angle formed by the
hypotenuse of triangle 100-1 and plane 93. In a similar fashion,
prism 98-2 has a substantially triangular cross-sectional shape and
may be defined by a height H2, a length L2, a distance D2, and an
angle .theta.2. Prism 98-3 also has a substantially triangular
cross-sectional shape and may be defined by a height H3, a length
L3, and an angle .theta.3. No distance D3 is shown in FIG. 7
because the perpendicular distance between the plane of the second
edge 104 and a respective corner of triangle 100-3 is zero, but
this specification contemplates that any cross-sectional triangle
may have any value D, including a negative value whereby a prism 98
extends beyond second surface 104. The selection of H, L, D and
.theta. is for purposes of convenience. As a matter of geometry and
trigonometry, the shapes of the prisms could also be equivalently
described with respect to other lengths or angles. As depicted in
FIG. 7, the triangular cross-sections 100 of prisms 98 are
proximate to one another, but the concept described herein is not
limited to the distances from one prism to another. Table I shows
certain possible ranges for each dimension for each prism 98. The
dimensions in FIG. 7 and Table I can also apply to the mirror-image
prisms 98-4, 98-5 and 98-6.
TABLE-US-00001 TABLE I Possible Ranges of Dimension for Prisms 98
Tolerance Tolerance Distance For Tolerance for Tolerance for Prism
Height H for Height H D Distance D Length L Length L Angle
.crclbar. Angle .crclbar. 98-1 about 0.3 about +/- 10% about 0.5
about +/- 10% about 0.5 about +/- 10% .crclbar.1 = about about +/-
10.degree. mm mm mm 40.degree. 98-2 about 0.2 about +/- 10% about
0.25 about +/- 10% about 0.25 about +/- 10% .crclbar.2 = about
about +/- 10.degree. mm mm mm 20.degree. 98-3 about 0.2 about +/-
10% about 0.25 about +/- 10% about 0.25 about +/- 10% .crclbar.3 =
about about +10.degree. or mm mm mm 5.degree. about -5.degree.
[0034] Referring now to FIG. 8, when light emitter 90 is active,
light emitter 90 emits light EL from an emitting surface of light
emitter 90. In a present embodiment the emitting surface of light
emitter 90 is substantially planar and parallel to plane 93. Where
light emitter 90 has an emitting surface with a shape different
from that shown in FIG. 8, including an irregular, rounded, or
otherwise non-planar emitting surface, such a light emitter can be
described as having a tangent plane from which light is emitted,
that tangent plane being substantially parallel to plane 93 and
substantially perpendicular to center-line 91. An idealized
representation of the scattered emitted light EL is shown in FIG.
8. Emitted light EL will in turn, become incident on various prisms
98, and commonly incident on given boundary of a given prism 98,
leading to a plurality of reflections, idealized representations of
which are shown in FIG. 9 as reflected light RL. Reflected light
RL, in turn, will undergo further reflections against substrate 78
to (for example) generate light L as shown in FIG. 4, leading to
transmitted light TL through the aperture 76 of each key 66.
[0035] As a variation of the embodiment in FIG. 8, not shown, light
guide 94 can be partially transmissive, such that some of the
emitted light EL is actually emitted from second surface 104. In
this variation, the emitted light EL from second surface 104 of
light assembly 86 can be used, for example, as a backlight,
although in an electronic device having a different structure than
portable electronic device 50.
[0036] It can be noted from FIG. 7 and Table I that prism 98-1, the
prism 98 nearest the center of light emitter 90 has the largest
angle .theta. and that prism 98-3, the prism 98 that is farthest
from the center of light emitter 90 has the smallest angle .theta..
In general, angle .theta. decreases for each prism that is farther
away from the center of light emitter 90. Indeed, light guide 94
can include any number "n" of prisms 98, where "n" is greater than
one. Furthermore, the angle .theta. for each prism 98 can be any
angle ranging from about one degree to about eighty degrees, where
the angle .theta. for each prism 98 becomes progressively smaller
according to the distance of a given prism 98 from the center of
light emitter 90. As rays of light are emitted in various
directions from the light emitter 90, some rays may be transmitted,
and others may be reflected (and thereby scattered), depending upon
each ray's path in the prisms. The angles can be selected to
produce any degree of scattering. In general, the prism 98 that is
closest to the center of the light emitter 90 has the largest angle
.theta. to produce a desired degree of scattering, and those prisms
98 further from the center of the light emitter 90 can produce
substantially the same degree of scattering with smaller angles
.theta..
[0037] As noted above, those skilled in the art will now appreciate
that the dimensions in FIG. 7 and Table I may also apply to the
mirror-image prisms 98-4, 98-5 and 98-6. It is to be reemphasized
that the foregoing is purely an example. In other example
embodiments, other numbers of prisms 98 can be provided, or only
some mirror-image prisms can be provided, or no mirror-image prisms
may be provided.
[0038] It can also be noted that FIG. 6, FIG. 7, and FIG. 8 show
only a cross-section of a light assembly 86 in one plane, but the
geometry of light guide 94 can be the same or different in
different cross-section planes. Indeed, light guide 94 can be
configured according to different three-dimensional shapes,
including, for example, using a pyramid for each prism 98. Pyramid
shapes having different numbers of sides are contemplated,
including tetrahedrons, square pyramid and pentagonal pyramids.
(Another example shape is discussed further below in relation to
FIG. 11.)
[0039] FIG. 9 provides another example embodiment, which shows a
top view of a light assembly 86a that is based on light assembly
86, and therefore like elements bear like references except
followed by the suffix "a". In light assembly 86a, fifteen prisms
98a are provided which are structured to generate reflected light
RLa in four directions all away from light emitter 90a, as shown in
FIG. 9. Again, the prism 98a closest to the center of light emitter
90a is the largest in size, and the other prisms 98a become
progressively smaller in size in proportion to their distance from
the center of light emitter 90a, to thereby generate reflected RLa.
In the embodiment of FIG. 9, each prism 98a is a four-sided pyramid
in shape and prisms 98a are arranged in a grid. To illustrate
further possible variations, in FIG. 9, the center of the grid of
prisms 98 is offset from the center of light emitter 90a, such that
more light is directed along arrow RLa-2, and less light directed
along arrow RLa-4. It should be understood that light emitter 90a
can also be centered in relation the grid of prisms 98, or offset
in other positions.
[0040] Furthermore, prisms 98a of light assemblies 86a can be
configured to only generate reflected light reflected light RLa-2
and RLa-4; or to generate reflected light RLa-1 and reflected light
RLa-3. FIG. 10 provides another example embodiment, which shows a
top view of a light assembly 86b that is based on light assembly
86, and therefore like elements bear like references except
followed by the suffix "b". In light assembly 86b, seven prisms 98b
are provided which are structured to generate reflected light RLb
in two directions all away from light emitter 90b, as shown in FIG.
10. As can be seen in FIG. 10, each prism 98b is four-sided, but
with each pair of sides having different lengths, where the longest
pair of sides direct the majority of light RLb. Again, the prism(s)
98b closest to light emitter 90b is(are) the largest in size, and
the prisms 98b become progressively smaller in size in proportion
to their distance from light emitter 90b, to thereby generate
reflected RLb. Each prism 98b is substantially rectangular and
arranged in parallel with each other. Light assembly 86b generates
reflected light RLb in two directions.
[0041] It is also to be reemphasized that prisms 98 can be
configured in different shapes. For example, another variation is
shown in FIG. 11, with a light guide 94c which can comprise a
central conical prism 98c-1 surrounded by concentric annular prisms
98c-2 and 98c-3. Those skilled in the art now will recognize that
light guide 94c has a cross-section as shown in FIG. 7. Of note is
that the shape in FIG. 11 can be expected to result in
substantially omni-directional reflections.
[0042] Other variations are also contemplated. For example, while
FIG. 7 and Table I show a particular exemplary configuration for
light guide 94, still further configurations are contemplated. One
such further configuration includes the option of spacing one or
more prisms 98 apart from each other. This configuration is shown
in FIG. 12, where a further light guide 94d is shown. In FIG. 12,
light guide 94d is substantially the same as light guide 94, except
that prism 98d-3 is spaced a distance G apart from prism 98d-2. The
distance G is measured along second surface 104, and reflects the
distance between the point where the length L2 of prism 98d-2 joins
with second surface 104, and the point where height H3 of prism
98d-3 joins with second surface 104. It is contemplated that G can
be in a range of about zero millimeters to about ten millimeters.
Furthermore, the distance G can be applied to any adjacent sets of
prisms 98d. For example, the distance G can be applied to the
spacing between prism 98d-1 and prism 98d-2. Or, the distance G can
be applied to the spacing between any additional prisms that are
included beyond prism 98d-3.
[0043] Various advantages are afforded by this specification. For
example, it can be possible to configure a device 50 having a
thickness T (as shown in FIG. 3) that is smaller than could be
configured without the benefit of this specification. Furthermore,
in certain manufacturing processes it is simpler to create tooling
to form substrate 78 rather than applying a reflective coating to
the underside of a keyboard 62 or equivalent structure.
[0044] While certain specific embodiments have been discussed
herein, combinations, subsets and variations of those embodiments
are contemplated. It is the claims attached hereto that define the
scope of time-limited exclusive privilege of this
specification.
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